Method of and apparatus for forming cylinders



u 1935- w. A. LlPPlNCOTT 2,011,535

METHOD OF AND APPARATUS FOR FORMING CYLINDERS Filed May 10, 1932 2 Sheets-Sheet 1 e Mina Aug. 20, 1935. w. A. LIPPINCOTT METHOD OF AND APPARATUS FOR FORMING CYLINDERS Filed May 10, 1932 2 Sheets-Sheet 2 Invent-sf We/Hs 4. Lippmcofh c.4114 r nggs srarss Parent @FFHCE METHOD OF AND APPARATUS FOR FORMING CYLINDERS Wells A. Lippincott, Oak Park, 111., assignor to. Ideal Roller & Manufacturing Company, Chicago,.llll., a corporation of Illinois Application May 10, 1932, Serial No. 6l0,514

37 Claims.

' This invention relates generally to the formation of cylindrical surfaces on rollers such as are used in printing presses and composed of rubber or like material. More particularly, the invention relates to the trimming of such rollers.

According to present practice, rubber rollers for use on printing presses are finished with a' true cylindrical surface by trimming to the desired size with grinding wheels'and finally bufling with fine abrasive surfaces. Owing to the softness andpliability of the rubber, the removal thereof by abrasion is a slow process usually requiring as many as twenty heavy and light cuts with coarse andfine grain abrasive taken at slow speeds and in different machines. Asa result, the time and labor involved inreducing a roller tothe desired exact diameter and with a smooth surface-is increased unnecessarily and the cost'of manufacture accordingly high. I

The primary object of the present invention is 'to' reduce the cost of producing rollers com-v posed of rubber or like material through the provision of a novel method of and machine for trimming the roller to the desired uniform diameter in a single longitudinal cut made at high speed. l I r In carrying out this object, the invention contemplates the use of a power driven knife edge positioned to enter the periphery of the roller in a manner such that, during rotation of the roller and advancement of the cutter longitudinally thereof, a thin ribbon-like helix will be sliced from thercller leaving a surface of uniform diameter which may be reduced readily to the desired smoothness. I I

. The invention also. resides in the novel manner of mounting and feeding the cutter so that a clean cut will be taken without the formation of a feather edge on the strip of material removed leaving a surface of uniform diameter which may be buffed readily to the desired smoothness.

Another object is to provide a novel method of and apparatus for removing the ribbon-like cuttings so as to avoid clogging of themachine.

Still another object is to combine, in a trimming machine of the above character, a mechanism for enabling thereduced surface to be buffed during the trimming operation.

accompanying drawings, in which Figure l is a fragmentary planview of a machine for trimmings. rubber cylinder in accordance with. the present invention.

Fig. 2 is a sectional view taken along the line 22 of Fig. 1.

Fig. 3 is a fragmentary view similar to Fig. 1 showing the manner in which the cutter is set preparatory to trimming the roller.

Fig. 4-is an enlarged sectional view taken at a point in advance of the cutter.

Fig. 5 is a fragmentary side elevational view of the roller and cutter in the course of trimming.

Fig. 6 is a sectional View taken along the line 66 of Fig. 4.

Fig. 7 is a cross-sectional view of the ribbon formed in the course of trimming, the section being'sho-wn on an enlarged scale.

' In the exemplary form shown in the drawings, theroller or cylinder to be trimmed comprises a vulcanized rubber sleeve 8 of substantial thickness carried by a shaft 9. During trimming the roller is rotated on its longitudinal axis and for this purpose is supported at one end by a conventional tail-stock "ion a lathe bed H. The other end is concentric with and detachably coupled to a headstock l2 rotated by suitable power means (not shown).

Preferably, the cutter comprises a metal disk I3 having a hub [4 fast upon the shaft l5 of an electric motor It by which the cutter is driven at high speed, approximately 3600 R. P. M. in the present instance. The motor is supported for vertical adjustment through the medium of a screw I1 threading onto a bracket !8 swingable about a pivot l9 and adapted to be clamped to a table 20 mounted on a carriage 2| which is movable transversely of the roller axis in either direction by turning a screw shaft 22, The carriage is supported by the bed H for movement longitudinally of the roller and is arranged to be fed in this direction at a uniform rate as by a power driven feed screw 23. 'With the motor thus 'mounted, it will be apparent that the cutter may be adjusted readily to vary the angle between the cutter and roller axes the height of the cutter, and the depth to which the cutter will enter the periphery of the cylinder to be trimmed.

Goodresults have been obtained with the carriage traveling longitudinally of the roller ata rate of approximately twenty inches per minute and the roller rotating through approximately eight revolutions during one inch of travel of the carriage.

Thecutter has a circular knife edge 24 disposed in a plane perpendicular to the shaft l5 and preferably having one flat side to facilitate sharpening. The size of the roller to be trimmed 'is a factor in determining the size of the cutter 1' ery of theroller to be trimmed along a helical 25 would be formed in short lengths. V I The ribbon is completed and severed from the to be used. For example, acutter eleven inches in diameter is preferably employed for trimming a roller approximately four inches in diameter although five-inch rollers may be trimmed with a cutter of this size. For rollers of substantially less diameter, a larger cutter, should be, employed whilea smaller cutter is preferred for rollers of larger. diameters! Thepresent invention contemplates mounting the cutter in a manner such that a short seg mental portion thereof will intersect the periphpath during advance of thecutter along the roller with the latter andfthe cutter rotating in the directions indicated by the arrows in Figs, 2

and and during such movement will slice a strip; or ribbon 25 from the rubber therebyv reducing the rollerto'the desired uniform diameter. To this end, thecutter is positioned with its leading "edge" portion spaced from theiroller'axis' a distance corresponding to the'diamete'r to" which duced; The points'at .Which thecutterlenters the rolleris to be finished arid-with its -axis' ex-. v tending transversely'ofbutoffset from theroller aXis so-that the cutter axis moves in a plane-2 6 parallel to a horizontal ,p lane 21 throu ghv the roller axis. Because of thisoffset relation of the cutter and roller axes, the knifeedge 24 engages the roller surface' at a point 28 .on'the u'nt'rimmeddiameter and passes outof contact with the rub 1 her at a; point 29 which, it willbe-observedds on the diam'etergto. which th e rolle'r is to be' reand leaves the "rubberare thus spaced axially and radially of theroller and both of the'pOints are.

disposed between theplanes' 26 and 2! with the point 29 adjacent the planefl; i

To '"obtainthe' above relation,"consideration fm ust be given to the depth ofthe cut to be taken and to the size of the cutter; with respect to the "size ofthe roller. For the amount ofrubber I which ordinarily is removed in trimming p rint-' ing press rollers, the desired relation is obtained with the cutter and rollerof the sizes above-described by loc'atin'gthe axis of the cutter at such a distance from the'roller axis that aradius "of the cutter through the-point 29 intersects the plane 2i at an "angle of approximately 30"degrees'.

To afford proper clearance between'the cutterblade and the trimmed portion'of' the roller, the shaft l5v preferably is inclined as'shown'in Figs. '1 and 3, the angle between the roller and the plane of rotationbf the knife edgebeing ap:

proximately 15 degrees in the present instance.

The "amount of material remo'ved during the cuti g Operation is determined by the distance be- -tween' the rolleraxis and that portion'o'f" the cutte'rj whicheriter's therubber, This I distance; is

' establishedpreparatory to:a cutting operation-by settihg thetable '29 through the medium of the hand-screw 2 2. i i 1 f With the *c'u'tter positioned as above'described, the strip 25'; roa s during the trimming operation is' bfftriangular I cross-section having a substantially straight uncut surface 30 equal inwidth "ltQ lthe distancethrough which itheicuttejri is ad- 'vanceddurin g each revolution of the'rolle'r and intersecting two slightly. curved surfaces 3i "and '32 which taper gradually toward eac'h other and intersect at a sharper acuteangle; "When arel- ,atively deep cut is takemthe strip 25 would}have a cross-sectional shape as shown on an enlarged "scale in Fig. 7 For shallower cuts, thesu'rface 3llmight be along thelinestfl arid30Pfthe surfaces 3| and 32 being correspondingly narrower.

surface.

' The entry of the-cutter'at' thedesired angle and the formation of a narrow strip is made possible by offsetting the cutter and roller axes Thus, it will be see that the width and angular relation of the surfaces 3! and 32 are determined by the depth of out which will vary with'diiferent rollers and also during trimming of any particular roller, if the untrimed surface of the latter is "not exactly concentric Withthe roller axis.

I Qrdinarily the cutter will not leave the rubber during any-one trimming operation and a continuous'ribbon'will be formed. But the cut may be so shallow and thedegree of eccentricity of the 'untrimmed surface so great that the cutter will just leave the uncut surface once during each revolution of the roller. In such a case, the strip roller by the formation of thesurface 32, the surface 3| being cut during the previous revolution of the roller. 'The curvature of the surfaces 3.! and 32 is due to thefact that they are formed by theintersection of a circular knife edge and a cylindrical surface, the degree'of curvature being determined by various factors including the relative sizes oflthecutter androller, and'the spacing of theroller and cutter axes.

With the presentmethod of slicing, it will be Q apparent that the angle at which the knife edge 24 enters, and leaves the surface 3i, cut during the previousrevolution'of the roller, corresponds to the angle'at which'the surfaces Elli, 3i and 32 iritersect. While this angleivaries with cuts of edge without' compressing the rubber materially which latter condition wouldresult in the for.- mation of ragged edges on the strip 25; and lack of; uniformity in the'diameterof the trimmed as above described. The spacing of these axes may be increased to some extent without: effect.-

"ingthe accuracy and uniformityv'of the cut but should not be increased by an amount such as would result ina substantially wider strip having thin feather edges. While the cutter and roller axes might be spaced closer together. such a change' 'in-spacingshould not, be surficient to lower thespoint 29 substantially below the plane t'ljotherwise, the rubber being carried toward 'theactive portion ofthe cutterblade would tend to wedge againstthe' side surface of the cutter and thereby become compressed, tending to pass the knife edge without'bei'ng uniformly cut to the required -depth. The latter condition is avoided with the preferred arrangement. above described and the r'ibbonfformed has 'a substantially straight edge resulting in the formation of a true cylindrical surface on the roller.

' Owing to the particular cross-sectional shape of the strip 25 resulting from the manner/in which the cutter-intersectsflthe rough roller surface, the trimmed surface is not perfectly smooth but is'formed with a narrow and extremely shallow spiral groove '33 defining a helical ridge 3 throughout the length of the roller. The depth fed along the roller. The angle betweenthe plane of rotatio'n'of the knife edge 24 andthe roller is also a factor in determining the depth [Of the groove 33, the.latter becoming deeper as -roller and with the rate at which the cutter is the inclination of the cutter is increased. In

order to form a shallow groove and thereby minimize the amount of bufiing required to form a smooth-surface on the roller, it is desirable to reduce the angle above referred to as much as possible at the same time allowing for proper clearance between the cutter and thetrimmed In the present instance, the

surface ofthe roller.

Means is provided for'bending the strip 25 10 awayf'rom the point at which it is completely 'formed'and conveying the; strip in a predetermined path away from the rotating parts so as to prevent the strip from Wrapping around such parts and clogging the machine. For this purpose, a stream of-iluid is discharged from a nozzle 35 against the strip 25 at and immediately beyond the point 28 at which, it will be observed, the transverse section of the strip is completely formed. In the present instance, the nozzle is directed downwardly in a direction generally longitudinally of the roller toward the trimmed end thereof and parallel. to the cutter (see Fig. 1) but one line offset with respect to the shaft i so as to carry the strip below the shaft. The

strip is thus conveyed away from the cutter falling'into a trough 3% formed by a casing 3 1 which constitutes'a guard for the cutter.

3 To provide proper lubrication for enabling a clean cut to be taken by the knife edge, water preferably is employedas the pressure fluid and is supplied to the nozzle through a hose 3S-supported .by an arm 'ts onthe bracket l8 so as to travel with the cutter and therefore remain in proper, position with respect to the cutter throughout the trimming operation. The volume of water used islarge enough to wash the strip 25 along the trough'36 maintaining alsubstantial length of the strip under tension thereby leading the strip along a predetermined path out of the wayjof the rotating parts. 1 trough 36 discharges into a receptacle 4| supported from the carriage 2 l. A- pump 42 .driven by an electric motor 43 withdraws. the water from thereceptacle, delivering the same continuously and under pressu're to the hose 38. As the ribbon25 and the water are l discharged into the receptacle, the ribbon is retained upon a screen 44 from whi'ch it is removed from time to time.

{1' Owing to' variations in the depth of the cut ftakenand the degree of eccentricity of the rough surface of the roller, the stiffness of the strip 25 cveran area indicated in dotted outline in Fig. 4

and elongated ina vertical direction so that regardless of the position at which the strip tends to bend, the water jet will always impinge .ontthe' strip .at the .proper point.

i In view of the accuracy with which the diameter of a roller can be reduced with the method above described, the amount of bufling with abrasi-ve' in order to produce a surface of the desired smoothness is reduced to a minimum. If desired,

the buiifing operation may be carried on simultaneously with the trimming operation. For this purpose, an abrasive carrying member such as a rotatable grinding disk 46 is mounted for move 'ment longitudinally of the roller'while in light contact with the trimmed surface thereof; Preferably, the disk is arranged on the side of the roller opposite the cutter and is adapted to contact the grooved roller surface a short distance behind the point at which the cutter acts. Herein the disk- 46 is fast on the shaft of an electric motor 41 mounted by a table 48 supported by the carriage 2i and adapted to be shifted toward and from'the roller by turning a screw shaft 49. In this way, the bufling disk moves withthe carriage and, when set to run in contact with the roller periphery, will remove the ridge 34 and reduce the roller to a true cylindrical surface-during the slicing operation. The presence of a substantial amount of water on the freshly trimmed portion of the roller greatly increases the efficiency of. the abrasive disk 46 enabling the ridge 34 to be removed completely at the same relatively high speed at which the roller is trimmed by the cutter. i

In the operation of reducing a roller to the desired diameter with the apparatus above 4 described, the cutter is first set to take a cut properly corresponding to the diameter to which the roller is tobe finished. This is accomplished as shown in Fig. 3 by mounting on the tail-stock ID .a disk 45 corresponding in diameter to that to which the roller is to be reduced. The cutter is then moved to a position in which the leading edge isdisp'osed opposite the disk 45 and the carriage shifted by means of the hand screw 22 until the edge of the cutter just contacts the disk. By manipulation of the hand screw 49, the disk 45 is then set in a similar way to correspond to the diameter to be formed. Next, the" carriage is moved to the opposite end of the lathe bed after which the roller is mounted in the machine. The motors l6 and 43 are then started and the feed screw 23 rendered active with the roller rotating in a direction indicated by the arrow-in Fig. 4. The remainder of the trimming operation occurs automatically, being complete after the cutter and the grindingdisk 46 have moved throughout the .length of the roller. Finally, the. roller is removed from the machine and any further polishing that may be necessary is carried on in a bufiing machine of well known construction.

-j By. the method above described it will be ap- ..parent that a roller may be trimmed to the desired diameter in'a single cut and athigh speed and simultaneously reduced to a high degree .of

smoothness. and finishing rubber rollers is reduced materially.

While the cutter, in the embodiment herein de- ,scribed, is mounted for bodily movement of its axis in a horizontal plane, itwill be obvious this 'axis might be movable in any other plane extending longitudinally of the roller within the scope of the present invention and the recitation in the claims ,of the horizontal location of the plane is not to be construed as a limitation.

,Iclaim as my invention:

1..A machine for trimming a cylinder com posedlof rubber or like. material comprising; in combination, means supporting said cylinder for rotation on its longitudinal axis, a carriage movable longitudinally of said cylinder, a rapidlyrotating circular knife blade mounted on said carriage and operable during movement thereof to slice a helical ribbon from the periphery of said cylinder, a liquid receptacle on said carriage, a

trough adjacent said-blade leading to said receptacle, a nozzle for discharging a stream of liquid againstsaid ribbon adjacent the point of formation thereof, said stream acting to convey .the ribbon along said trough, means acting'to separate the liquid from said ribbon and allow the liquid to flow into said receptacle, and means for Accordingly, the cost of trimming trimming to enter the, periphery of said cylinder mental portion of the leading edge of said cutter entering said material l11th8 untrimmed' diameter and leaving the material, on the diameter to which the cylinder is to be trimmed and at a point axially spaced behind the point of entry, and means rotatably carrying said cylinder and effecting I relative longitudinal movement between the cylinder and said cutter.

. 16; A machine for reducing, the diameter of a cylinder composed of rubber or like material comprising, in combination, a power driven circular knife having a tapering edge adapted during to a depth corresponding to the diameter to which the cylinder is to be reduced, said edge leaving the rubber at a point on the reduced diameter spaced from the point of entry both circumferentially and axially of the cylinder, means rotatably carrying said cylinder at a uniform rate to present successive circumferential portions of the cylinder'to said knife, and means for feeding said knife at auniform rate longitudinally of said cylinder Y 1,7. A machine for trimming a cylinder composedof rubber or like material comprising, in

combination, a rapidly rotating disk having, its

axis extending transversely of the axis of the cylinder and spaced therefrom a distance corresponding to the diameter to which the cylinder is to be reduced, means supporting saidgdisk and cylinder for relative bodily movement of their axes in spaced parallel planes, said disk'having a circular knife edge with a segment thereof intersecting the peripheral portion of the cylinder and passing out of contact with the material on a diameter less than that of the cylinder, means rotatably carrying said cylinder and means for q effecting said relative bodily movement.

- 18. A machine for trimming a cylinder composed of rubber or like material comprising, in combination, a rapidly rotating disk having its axis extending transversely of the cylinder and a knife edge with a segmental portion adapted to 1 enter the cylinder periphery to a depth corresponding to the diameter to whichthe cylinder is to be reduced, means supporting said disk and the cylinder for relative bodily movement of their axes'in spaced parallel planes wherebysaidedge enters and leaves said material at points axially spaced alongthe cylinder, means rotatably carrying said cylinder, and means for effecting said relative bodily movement at a uniform rate.

19. A machine for reducing to a predetermined diameter a cylinder composed of rubber or like material comprising, in-combination,;a rapidly rotating disk having a knife edge positioned so that a segmental portion enters the periphery of above the cylinder axisa said cylinder, means supporting said disk and cylinder for relative bodily movement of their axes in spaced parallel planes extending longitudinally or. said cylinder.

V 20. A machine for trimming a cylinder composed of rubber or like material comprising-in combination, power driven means supporting and rotating said cylinder on its longitudinal axis in a'horizontal position, a power driven horizontal shaft supported for bodily movement longitudinally of said cylinder, a cutter disk on said shaft having a circular knife-edge disposed in a vertical plane slightly inclined with respect to and making an obtuse angle with the untrimmedportion of the cylinder, the axis of said shaft being spaced distance such that the leading-edge portion of the blade enters the cylinder at a point substantially above a. horizontal plane through the roller axis andleaves the roller at a, point. disposed above but closely adjacent inglongitudinally of. said cylinder, the spacing of said planes and of the disk relative to the roller axis ibeingisuch. that a segmental portion of said edge enters and leaves the periphery of the cylinder between. saidpl'anes with the point of leaving disposed closely adjacent: said plane through the cylinder axis.

' 22., A machine for reducing toapredetermined diameteriarcylinder composed of rubber ,or like material comprising, in combination, a rapidly rotating .diskhaving. a. knife edge, means sup porting said disk and cylinder for relative bodily movement of their axes in parallel planes extending longitudinally of said cylinder, the spacing ofsaid planes. 3116.101 the disk relative to the rolleraxisbeing such that a segmental portion of said edgeenters the periphery of said cylinder between said planes and leaves the materialadjacent said plane through the cylinder axis, andmeansrotatablysupporting said roller.

23. A machine for reducing to a predetermined diameter a cylinder composed of rubber'orlike material comprising, in combination, a powerdriven disk having a knife edge rotatable in-a vertical :plane, means supportingsaid disk and cylinder for bodily movement of the axes in parallel horizontalplanes withthe plane through said disk axisdisposed above the roller axis a distance such that a segmental portion of said knife edgeenters and leaves the peripheryof the cylinder between said planes, and means rotatably supportingsaid roller to rotate in a direction to carry the rubber upwardlypast said segmental portion.

24. A :machine for trimming and buffing a cylinder composed of rubber or like material comprising, in combination, means supporting and rotating said cylinder on its longitudinal axis, a-powertdriven cutting disk mounted .for bodily movement relative to said roller in a direction longitudinally of the latter and positioned to slice ahelical ribbon from the periphery of the cylinder during such movement whereby to reduce-the diameter of thecylinder, an abrasive element engageable with said surface of the cylinder on its reduced diameter and movable with said disk whereby to buff the reduced surface progressively during formation of said ribbon.

251 Amachine for reducing the 'diameterof a, cylinder composed or rubber or like material comprising, in combination, means supporting and rotating said cylinder on its longitudinal axis, a carriage mounted for movement at a uniform rate longitudinally of said cylinder, a power driven knife edge on said carriage positioned to slice a helical ribbon'from the periphery of said cylinder during movement of said carriage whereby to reduce the diameter of the'cylinder, an abrasive-carryingmember supported by said carriage on the side of said cylinder opposite said knife edge and positionedfor cutting engagement with the cylinder. surface on its reduced, diameter and at a-point adjacent" the p o rtion being cutbys'aid k-nifeedgee v,

ment and rotatibn ofhthe cylinder"wherebymto reduce the-'- diameter o'f the :cylinder, and an abrasive element operable "during said relative bodily lmovement to? buff the cylinder "surface:

on 'said reduced diameter. a a

I 27'; A'machine-for *trimming iandbtifiing: a cylinder composed of rubber: and like material-- comprising; -in combination; a r power driven .cut

ting disk; means rotatably supporting said disk.

and cylinder for relative'bodily movement of their axes in spaced parallel 'splanesg said :disko be- I adjacent the point'cf complete formation of. said:

ing positioned'ito Slice al helical rribbon'from the cylinder periphery during 1 such irelativel move! ment and 1 rotation of the I cylinder whereby to I reduce the diameter of the cylinder, meansiproV-o;

vidingY-a "jet. of liquid directed toward said disk ribbon,. and an labrasive element operable during '5; 29. 111 a, machine slicing-f a rotation of the cylinder and l said. bodily moveimentcto grind lthecylindricali surface of .reduced diameter,; said. element contacting l the 'lattezt surface: adj acentl the point of slicing whereby the liquid retained on thesurface.isutilizedjas a s w cylinder composed of-rubber or like material comlubricant ingrinding.

028. The method of trimming mammal a cylinder, of rubber or'likematerial which com-..

prises-slicing a helicaliribbon' of triangular cross section from'the peripherylofsaid cylinder leaving a spiral ridge on theusurface of reduced diameter, and bufling ofi said ridgeprogressively alongsaid cylinder during-the formation ofjsaid helix from the periphery of a cylindrical, rubberv roller: to trim the roller to;a uniform diameter, the combination of means rotatablyssupporting said roller, a power driven rotarycutter having acircular'peripherali knife edge and, supported with its rotational axis extending transversely of and slightly inclined with respect to theyroller axis and disposed'in a plane parallelto-the latter,

a segment of"saidblade projectin'grinto'the ,cylin der defined by the roller. periphery. to l the depth to which the roller is to be trimmed, and means for effecting; relative bodily movementibetweensaid cutter and roller in a direction longitudinally of the latter.

30; In a machine for :{slicingoa ribbon-like" helix from the periphery of ;a cylindrical rubber roller, the combination of means for Su porting and rotating said rolleron its longitudinal axis,"a circulanknife edge rotatably supported with its rotational axis extending transversely of andin a plane, parallel to the rolleraxisand a segment of its gperiphery projecting into the cylinder defined by the roller periphery tothe depthfto which the roller is to be trimmed,;means for efiecting relative bodily movement between said knife edge and said rollerl in adirectionj longitudinally ,of the latter, empower, driven means for rotating said knife edge atja speed substantially greater than the speed of rotation of the roller; 7

31. In a machineforthepurposedes'cribed; the combination of means for supportingand rotat ing a rubb'er roller, and apowerrotatedcircular aemsss knife edge positioned-to slice a ribbon-likehelix from the periphery of the rollerupon relative.

bodily movement of 'theroller and knife edge in 1 a direction longitudinally of the roller, and means for effecting-such relative movement.

32; 'In'a machine of the class described, the

combinationof means for supporting a roller and rotating the; same about its longitudinal axis, a circular knife edge disposed inv a'plane substantially parallel to theroller axis and spaced'there from to enter and leave the roller upon its untrimmed and trimmed diameters respectively whereby to slice a helical ribbon of I triangular cross-section from the periphery'of the roller rotating the same about its longitudinal axis, a

circularknife'edge disposed in a plane substantiallyparallel to the roller axis and spaced there-- from to enter and leave the roller upon its untrimmed and trimmed diameters respectively whereby fto 'slice a helical ribbon of triangular cross section'from the'periphery of the roller during relative movement of the knife edge and roller in a directio-nlongitudinally ofthe latter while theroller is'being rotated,"and'powermeans for ro' tating said knife edge at a speed substantiallygreater' than-the speedof rotation of the roller.

ee-11 116 method or reducing the diameter of a" prising rotating the cylinder on its longitudinal axis; positioninga rapidly rotating circular knife edge with its rotationalaxis extending transverse ly of. the cylinder axis and with a segment of the edge adapted'to'enter the cylinder periphery at an acute angle, and causing relative movement between the knife edge'and cylinder longitudinally of theilatte-r and at a uniform rate wherebyto removea helical ribbonfroni the periphery of the cylinder; v I I -35. i i-machine for reducing. the diameter of a cylinder composed" of rubber or. like -materialcomprising, in combination; a'power driven cut-- ting element having; a knifeedge adapted during trimming to enter'the periphery of the cylinder to a'depth' corresponding to the'diameter to which the cylinderisto be reducedgsaid edge entering and leavingthe material of the cyliriderat points axially spaced along the cylinder, and means for efiectingrelative movement between the" cylinder and said cutting element so that the latter will positioned to slice a helical ribbon from the 0311'- index" periphery-during such relative movement and rotation of the cylinder whereby to" reduce the diameterof the cylinder, means'providing a jet of liquid directed toward said element adjacent thev point of complete formation of saidribbon whereby some ofsaid liquid is retained on, the trimmedicylindrical surface and an abrasivemeans operable, during rotation of the cylinder and'said b'odily movement to grind the cylindrical surface, of reduced diameter; said means con-.

tacting-thelatter-surface adjacent the point of slicing whereby the liquid retained on the surface the roller periphery so as to slice a ribbon-like is utilized as a lubricant in grinding. helix from the periphery of the roller upon rela- 37. In a machine for the purpose described, the tive bodily movement of the roller and knife edge combination of means for supporting and rotatlongitudinally of the roller, and means for effect- 5 ing a rubber or like roller, a power driven knife ing such relative movement.

edge angularly positioned relative to both the longitudinal and circumferential dimensions of ELL LIP I C TT, 

